预处理气氛对铁离子掺杂的氧化钛纳米管微结构和光催化活性的影响

Effects of pre-annealing atmosphere on microstructure and photocatalytic activities of Fe-doped titania nanotubes

摘要:

本文通过在空气和还原性气氛中煅烧铁离子掺杂的锐铁矿纳米粉体,并且采用水热合成法制备了具有锐铁矿结构的纳米管,研究了它们的微结构和物理化学行为。研究发现,与在空气中煅烧相比,还原性气氛下煅烧引入了低价态Fe₂₊和Ti₃₊离子以及更多的表面吸附氧,纳米管的比表面积、亚甲基蓝吸附能力以及光吸收阈值得到显著提高。1 mol% Fe 掺杂以及还原处理产生了最高的吸附和光催化活性及其降解持久性,过多掺杂反而降低了光催化性能。此外,水热合成引起纳米管的含铁量下降。

Abstract:

The nanotubes with an anatase structure were hydrothermally synthesized using the Fe-doped anatase nanopowder precursors that were annealed in air and reductive atmospheres. The microstructure and physicochemical properties of the nanotubes were comparably investigated. Experimental results show that the reductive pre-annealing yielded more surface-chemisorbed oxygen by introducing lower valance Fe₂₊ and Ti₃₊ ions. The specific surface area, methylene blue adsorption and photoabsorption threshold of the nanotubes were greatly enhanced by the reductive annealing when comparing with annealing in air. 1 mol% Fe doping and the reductive annealing yielded the highest adsorption, photocatalytic efficiency and durability for degradation of MB solution; extreme Fe doping decreased the photocatalytic efficiency. The Fe content of the nanotubes was decreased by the hydrothermal synthesis, especially in the case of annealing in air. Moreover, the action mechanism of the Fe doping and reductive annealing was discussed.